Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$233.81	5.105%	$245.746	$245.75	$245.75	$245.70
Purchase #2	$69.53	4.202%	$72.4517	$72.45	$72.45	$72.50
Purchase #3	$236.74	13.804%	$269.4196	$269.42	$269.40	$269.40
Purchase #4	$119.55	6.304%	$127.0864	$127.09	$127.10	$127.10
Purchase #5	$69.95	13.551%	$79.4289	$79.43	$79.45	$79.40
Purchase #6	$116.60	5.783%	$123.343	$123.34	$123.35	$123.30
Purchase #7	$151.57	3.532%	$156.9235	$156.92	$156.90	$156.90
7 purchase totals =	$997.75		$1,074.3991	$1,074.40	$1,074.40	$1,074.30